Effect of Thickness of InP Nucleation Layer on the Two-Step Growth of InP on Si(001)

InP nucleation layers with different thicknesses were grown on Si(001) substrates by gas-source molecular beam epitaxy (GSMBE), and the two-step growth technique was used to overcome the large lattice mismatch (8%) between the InP nucleation layer and Si substrate. The surface morphology and microstructure were investigated by using an atomic force microscope (AFM) and transmission electron microscopy (TEM). High-resolution X-ray diffraction (HR-XRD) measurements were carried out to characterize the crystal quality. It was found that a too thin nucleation layer will lead to an uneven distribution of atoms on the surface, resulting in a poor crystalline quality of the InP epitaxial layer. The thicker the low-temperature nucleation layer is, the better the crystallization quality of the InP high-temperature layer will be.